Newb: XT701 and Camera (still and video) questions

I have a stock, unrooted, unlocked XT701 running 2.1.update1 on ATT in the US. I've been fiddling with it on and off for a while. I'm still hoping for a froyo update soon; if not I might root the phone. The documentation that came with the phone is rubbish.

For some reason, it seems easier to find information (on cameras) aimed at developers than information aimed at users. So, here are my questions:

1. On the side of the phone, near the shutter-release button, what is the small button with the three straight lines for?

2. I've seen references to the "standard" camera app, but I can't find it in order to launch it. Where is that app, or is it a froyo thing?

3. Since I can't find the standard app, I grabbed a copy of Camera360. It (usually) takes still pictures OK. My specific problem is that when I try to take a picture something and upload it to twitpic, Camera360 appears and lets me take the picture. When I exit out of Camera360 and the twitter client reappears, it tells me that it could not find a picture. What am I doing wrong?

4. I don't see how to take video of any kind. How do I take video with this phone? Is this something hidden in Camera360 somewhere, or do I need something else from the app store.